For the color-effects it was felt that just the right man must be found
or the result would be disastrous. The choice fell on Jules Guerin, long
accepted as one of the finest colorists among the painters of his time.
He followed the guidance of the natural conditions surrounding the
Exposition, the hues of the sky and the bay, of the mountains, varying
from deep green to tawny yellow, and of the morning and evening light.
And he worked, too, with an eye on those effects of illumination that
should make the scene fairyland by night, utilizing even the tones of
the fog.